1. Field of the Invention
Embodiments of the present invention generally relate to a method and apparatus for conditioning a polishing pad.
2. Description of the Related Art
Electrochemical Mechanical Processing (ECMP) is a technique used to remove conductive materials from a substrate surface by electrochemical dissolution while concurrently polishing the substrate with reduced mechanical abrasion as compared to conventional Chemical Mechanical Polishing (CMP) processes. ECMP systems may generally be adapted for deposition of conductive material on the substrate by reversing the polarity of the bias applied between the substrate and an electrode. Electrochemical dissolution is performed by applying a bias between a cathode and a substrate surface to remove conductive materials from the substrate surface into a surrounding electrolyte. The bias may be applied to the substrate surface by a conductive contact disposed on or through a polishing material upon which the substrate is processed. The polishing material may be, for example, a processing pad disposed on a platen. The processing pad is an important aspect of the ECMP process. The processing pad must have the appropriate mechanical properties for substrate planarization while minimizing the generation of defects in the substrate during polishing. A mechanical component of the polishing process is performed by providing relative motion between the substrate and the polishing material that enhances the removal of the conductive material from the substrate.
ECMP normally comprises removal of bulk conductive material with a high removal rate, removal of a residual conductive material with a moderate removal rate, followed by removal of a barrier layer. Efficient removal of the conductive material depends upon uniform biasing of the conductive material. As a result, uniform local electrical contact between the polishing material and the substrate surface is highly desirable. For this reason, pad conditioning procedures (break-in procedures) and apparatus have been developed to condition pads so they can provide superior local electrical contact.
Therefore, there is a need for a method and apparatus for evaluating the ability of a conditioned polishing material to provide uniform local electrical contact to a substrate surface.